Sendmail: How does one blacklist annoying spammers?

[Alan Cox]

> I believe that's what SPF is supposed to solve.  Sites advertise in
> their DNS records which the "official" outgoing email servers are. 

Spammers advertise SPF records of 'the whole internet' (normally split
into chunks to confuse checkers) and turning on SPF checking naïvely
simply helps the spam get through.

SPF also breaks forwarding in many cases and has other problems
including mailing list interactions.

The lack of massive uptake is not I suspect chance..

Alan